1. Field of the Invention
The present invention generally relates to components for internal combustion engines and more particularly to an intake manifold for use on high output engines including diesel engines found on semi-trailer trucks.
2. Description of Related Art
It is well established that power and torque output are of utmost importance in the field of semi-trailer and semi-tractor trailer truck engines. Certainly in many instances power and torque are maximized at the expense of fuel economy. However, with the onset of ever-increasing fuel costs, efficiency has been brought to the forefront of tractor-trailer technology. As many tractor-trailers have an average operational life expectancy exceeding ten (10) years, there is a definite need to find ways to increase the efficiency of existing engine designs. Indeed, newer and more efficient engine designs are always in the pipeline, but it is not always the most economical solution to swap out equipment or send otherwise reliable and durable tractor-trailer engines to end-of-life.
Diesel engines have long been known to provide greater torque and often better fuel efficiency than gasoline engines. Generally speaking, a diesel engine, also known as a compression-ignition engine, is an internal combustion engine that uses the heat of compression to initiate ignition and burn the fuel that has been injected into the combustion chamber. This contrasts with spark-ignition engines such as a gasoline engines that use a spark plug to ignite an air-fuel mixture. Ignition inside a diesel engine is achieved when one or more pistons reciprocating inside a cylinder physically compresses air introduced into the cylinder to the point where the air reaches a high enough temperature to ignite vaporized diesel gasoline injected into the cylinders. The vaporized fuel then combusts and drives the piston outward from the cylinder, supplying power to the crankshaft.
Generally speaking, the higher the compression ratio of the engine, i.e. the ratio between the volume of the cylinder at its largest capacity to the volume at its smallest capacity, the more efficient the engine. Because diesel engines do not have fuel in the cylinder before combustion is initiated, a large amount of air can be loaded in the cylinder without pre-ignition and therefore higher compression ratios can be achieved as compared to gasoline engines. As having more air in the cylinders allows more fuel to be burned at a more efficient rate, optimizing the volume of air in the cylinders is the key to unlocking a diesel engine's efficiency and power.
Many solutions for maximizing air flow into the cylinders have been used, such as superchargers and turbochargers (or combinations of the two) but there has not been much thought put into the actual air intake manifolds of the these engines. Traditional intake manifolds for diesel engines, particularly those used on tractor-trailer engines, such as the Volvo D13 motor, comprise a rudimentary “shoe box” design, shown in FIG. 1. These intake manifolds have a basic box-shaped plenum with an air inlet and an open bottom in flow communication with a cylinder head in which the cylinders and cylinder valves are seated. Typically the inlet of the intake manifold is in flow communication with an intercooler that receives compressed or “forced” air from a tuborcharger. Such a design is prone to significant flow and pressure losses and substantial variance in airflow and pressure from one cylinder to the next as inlet air tends to collect at the rear end of the plenum, causing more air to enter the cylinders at the rear leading to a leaner fuel/air ratio as compared to the cylinders toward the front of the plenum, which receive less air and therefore have a richer fuel/air ratio. An imbalance in airflow rates and in turn cylinder pressure causes an uneven distribution of power across the cylinders leading to decreased overall efficiency, power output, and fuel economy as the “richer” cylinders in effect pull the “leaner” cylinders around the crank shaft. Accordingly, there is a need in the art for an improved bolt-on replacement intake manifold design, particularly useful for large diesel engines, that provides measurably increased efficiency and fuel economy by correcting the imbalance of air flow rates and pressure across the cylinders.
Several attempts have been made to design intake manifolds that increase power and output, however none are sufficiently engineered to overcome the existing problems with manifolds for large diesel engines.
For example, U.S. Pat. No. 7,073,473 to Boyes describes a tunable intake manifold for directing a flow of air between a plenum and an internal combustion engine. The tunable intake manifold includes a manifold housing defining an interior. The manifold housing has a plurality of runner walls extending through the interior. The tunable intake manifold also includes a slider having a slider wall having an angled portion separated from a primary portion by a curved portion. The slider wall extends through the interior of the manifold housing. The slider wall cooperates with the runner wall to define a runner having a defined cross sectional area for transporting the flow of air therethrough. The slider is slidably engaged with the manifold housing for moving the slider wall relative to the runner wall to selectively change the defined cross sectional area of the runner, such that the volume of air passing therethrough changes with the movement of the slider. The angled portion of the slider travels parallel to the runner wall at a transmitting end of the runner.
U.S. Pat. No. 6,571,760 to Kallander describes an intake manifold comprising a first end, an opposing second end with an end wall, and at least a first internal wall, if the body of the air inlet manifold has a circular cross-section. Alternatively, the air inlet manifold body has a rectangular cross-section, with several internal walls. The air inlet manifold extends in a longitudinal direction from the first end to the second end. The air inlet manifold has an air inlet at the first end and at least one distribution chamber for air extending along the longitudinal direction and restricted by at least the first internal wall. The air inlet manifold also has at least one air pipe for each cylinder. The pipes are distributed along the longitudinal direction. The pipes or runners protrude perpendicularly from the manifold. For at least one of the pipes, a profile between the first line and the second line located proximate to the air inlet has different curvature than a profile between the first line and the second line located distant from the air inlet. The profiles may advantageously be in the form of curvatures and the first area is preferably greater than the second area. Preferably, the profile between the first line and the second line located proximate to the air inlet has a greater curvature than the profile between the first line and the second line located distant from the air inlet, and preferably the first area is greater than the second area.
U.S. Pat. No. 5,005,532 to Shillington describes a manifold characterized by a plenum surrounded by runners that spiral around the plenum sidewall to the entrances to the engine cylinders. The circumferential extent of each runner exceeds 360 degrees about a longitudinal axis of the plenum.
Japanese Patent JP2003074357 to Mamisa describes an intake manifold having a plurality of intake branch passages for distributing intake air from an intake collecting part of an intake manifold to the respective cylinders. The branches or runners have bend portions bent toward the centers of the respective related cylinders, on an intake branch passage side of connection portions to intake ports on a the cylinder head. A bend portion connected to a cylinder more distant from an intake-introducing portion of the intake collecting part has a larger curvature. This manifold is designed for gasoline engines and provides two runners per valve in a complex configuration.
It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed. However, in view of the intake manifolds in existence at the time of the present invention, it was not obvious to those persons of ordinary skill in the pertinent art as to how the identified needs could be fulfilled in an advantageous manner.